[Elecraft] RTTY Operations

[Bob Nielsen]

On Thu, Jan 30, 2003 at 09:37:48AM +0000, Julian (G4ILO) wrote:
> Am I missing something here? I've worked RTTY using my normal data mode 
> filters which are centered on 1200Hz. It doesn't matter what the frequency 
> is, any more than it does for any other data mode. If you're using MixW, 
> you can just see the RTTY signal in the waterfall and click the cursor on 
> it, just like in PSK.
> 
> I'm not quite sure why RTTY specifies the tone frequencies, though 
> presumably in older radios where the FSK is produced in the transceiver by 
> keying the hardware, the actual shift from the BFO frequency was set up for 
> that amount.

Long before sound cards were even a glimmer in the eyes of the folks at
Creative, RTTY was normally detected with Terminal Units which had
fixed filters at audio frequencies.  Additionally, in the pre-packet
days there was a fair amount of RTTY AFSK activity on VHF FM, in which
the actual mark and space frequencies were as important as the shift. 
I retired my Model 15 and TU about 20 years ago, but I still have a few
of the ubiquitous 88 mH toroids (which were quite popular for filter
construction) around somewhere.

73, Bob N7XY

-- 
Bob Nielsen, N7XY                          n7xy@n7xy.net
Bainbridge Island, WA                      http://www.n7xy.net
IOTA NA-065, USI WA-028S